Five kilometres long, it was built in the 13th century to bring water from Monte Pacciano to the Fontana Maggiore. Work began slowly in 1255 and, under the guidance of Fra Bevignate and Boninsegna da Venezia, was finally completed in 1280. Due to continuous maintenance problems, a new aqueduct was built in 1835. The last stretch of the old aqueduct was transformed into a characteristic terraced footpath above the huge medieval arches.